Björn Rust (he/him) is a post-industrial designer cum researcher, innovator and educator, developing context-sensitive innovation practices for people, planet and beyond.

Recent writings

  1. Opportunity hoarding
  2. Doing away with bullshit
  3. The course of my life, so far

Ego depletion and morality

The brain demands a great deal of energy to function. In fact, something in the order of 20% of our body’s total energy consumption is attributed to the brain. We can feel the effects of this energy requirement, but we don’t always appreciate how it manifests in our decision making.

While reading Daniel Kahneman’s Thinking, Fast and Slow, I was made aware of a study by Roy F. Baumeister, who coined the term ego depletion. His findings, as Kahneman put it, were that:

The nervous system consumes more glucose than most other parts of the body, and effortful mental activity appears to be especially expensive in the currency of glucose. When you are actively involved in difficult cognitive reasoning or engaged in a task that requires self-control, your blood glucose level drops. The effect is analogous to a runner who draws down glucose stored in her muscles during a sprint. The bold implication of this idea is that the effects of ego depletion could be undone by ingesting glucose, and Baumeister and his colleagues have confirmed this hypothesis in several experiments.

If we accept that morality is essentially the process of deciding between right and wrong, is it any wonder that making moral decisions becomes more difficult as we fatigue? This is a narrative that we have been made to feel comfortable with by the way of Baumeister’s study. For example, »I am tired therefore I will reach for that hamburger rather than this carrot«. But that narrative has been thrown into some doubt in recent years. For one, we now understand that the brain doesn’t consume all that much extra energy under load.

So why is it that we don’t consistently make moral decisions? It’s possible that it is the oft-held belief that morality is a zero-sum game, with gains for one cause coming at the expense of another. We tend to keep a moral balance sheet in which we tally what we understand as good choices against bad. Riding our bike to work rather than driving is entered in the positive column, which we feel justifies a beef burger for lunch.

I can’t be certain, but it seems that the narrative around ego depletion and decision fatigue is a self-fulfilling prophecy. Stanford psychologist Carol Dweck et al. concluded that:

only those who believe that willpower relies on a limited resource show poor performance without sugar and a replenishment effect with sugar. We suggest that those who believe that willpower is not highly limited show no replenishment effect when given sugar because they do not need one and/or because they are not vigilant for cues about the availability of mental energy.

In other words, belief drives behaviour. So if one wishes to remain vigilantly ethical, beware of that metal tally rather than one’s blood sugar level.

Inspired by: Fast Company
Reference: Scientific American


Return to top